1. Field of the Invention
The present invention generally relates to a cleaning unit used for an image forming apparatus, such as a copier, a facsimile, or a printer, and an image forming apparatus and an image carrying unit including the cleaning unit.
2. Description of the Background Art
In general, image forming apparatuses using electrophotography include a photoconductor to form a latent image and a visible toner image developed with the use of toner, for example. In such image forming apparatuses, waste materials (e.g., excess toner) remaining on the photoconductor may be removed by a cleaning unit after a process of transferring the toner image. The cleaning unit may employ a blade-cleaning method, in which a blade, typically made of rubber, is contacted against the photoconductor to remove toner from the photoconductor.
In such a blade-cleaning method, the cleaning unit generally includes a cleaning blade and a brush roller, wherein the brush roller is located upstream from the cleaning blade in a surface moving direction of the photoconductor and is used to assist in cleaning function of the blade.
Further, the cleaning unit may include an ejection member, for example a toner recovery coil, to transport waste materials (e.g., excess toner) removed from the surface of the photoconductor to a transport route outside of the cleaning unit. The waste materials transported to the transport route may be further transported to a development unit or a waste toner bottle, for example, as in Japanese Patent Application Publication No. 2005-338880 (hereinafter “JP-2005-338880-A”).
In general, toner removed by the cleaning blade drops from where the cleaning blade contacts the photoconductor. Accordingly, it is preferable to dispose the toner recovery coil at such a location.
However, the photoconductor is typically surrounded by several other units (e.g., a charge unit, a development unit, a transfer unit, etc.), which need to be placed around the photoconductor in addition to the cleaning unit. Accordingly, it may be difficult to allocate a greater space only for the cleaning unit.
In light of such configuration, the cleaning unit may include a supplemental transport member for transporting the removed toner to a transport-effective area of the toner recovery coil (referred as “an exhaust transport route”).
Thus, for example, in JP-2005-338880-A, the cleaning unit includes a cleaning blade, a separation unit, and a toner recovery coil. In such a configuration, toner removed by the cleaning blade drops to the brush roller placed beneath a location where the cleaning blade contacts the photoconductor. In such a configuration, the brush roller is used as a supplemental transport member to transport toner to a transport-effective area of the toner recovery coil, and the separation unit is used for separating toner adhering to the brush roller at a position above the toner recovery coil.
However, use of the brush roller may involve higher manufacturing costs because brush fibers need to be wound and fixed on a metal core to manufacture the brush roller, and complex fiber processing may be required for the brush fibers.
The cleaning unit may omit a brush roller and include only a cleaning blade as a cleaning member. The cleaning performance of the cleaning blade is enhanced by using lubricant, thus striking a balance between cost and performance.
However, if the cleaning unit has no brush roller, a transport device for transporting toner removed by the cleaning blade to a transport route for ejecting toner (e.g., exhaust transport route) may be required, and in view of manufacturing cost, the transport device may need to be less expensive than the brush roller. The above described configuration and cost considerations must be taken into account when designing a cleaning unit including a cleaning member such as a blade, which contacts an object to be cleaned.